• Korean Journal of Microbiology
• /
• v.36 no.1
• /
• pp.58-63
• /
• 2000

A bacterial isolate capable of degrading benzoate was selected from wastewater of Yocheon industrial complex and examined its biochemical characteristics and fatty acid composition. The isolate was identified as Klebsiella oxytoca strain C302. The strain C3O2 degraded catechol, protocatechuate, and 4-hydroxybenzoate as well as benzoate. The strain grew on and degraded 0.5 to 1.0 mM catechol most actively in MM2 medium at pH 7.0 and $30^{\circ}C$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.6
• /
• pp.136-144
• /
• 2004

Dissolved gas in oil analysis has been used for fault diagnosis of oil immersed insulation. In this paper to improve the reliability in deciding the degradation causes of the oil immersed insulation, we carried out electrical and thermal degradations for the insulations, and analyzed the characteristics of dissolved gases distribution on each situation. As a result more reliable faults discrimination is possible if we use the interrelation of factors like key gases and gas compositions of hydrocarbon gases and ratios of CO/$CO_2$.

• Korean Journal of Microbiology
• /
• v.54 no.1
• /
• pp.46-52
• /
• 2018

Biodegradation pathway of dibenzofuran (DBF) of Novosphingobium pentaromativorans US6-1, a high-molecular-weight polycyclic aromatic hydrocarbons degrading strain, was investigated via analysis of metabolic intermediates and transcriptome. As a result, 3(2H)-benzofuranone, a basic skeleton of the metabolic intermediates produced by lateral dioxygenation process, was detected as an intermediate. RNA-Seq analysis confirmed that most of the expressed genes upon exposure to DBF were related to the lateral degradation pathway. Based on these results, the biodegradation pathway of DBF by N. pentaromativorans US6-1 was proposed.

• 한국생물공학회:학술대회논문집
• /
• 2000.04a
• /
• pp.89-91
• /
• 2000

Polynuclear aromatic hydrocarbon (PAH) compounds are highly carcinogenic chemicals and common groundwater contaminants that are observed to persist in soils. The adherence and slow release of PAHs in soil is an obstacle to remediation and complicates the assessment of cleanup standards and risks. Biological degradation of PAHs in soil has been an area of active research because biological treatment may be less costly than conventional pumping technologies or excavation and thermal treatment. Biological degradation also offers the advantage to transform PAHs into non-toxic products such as biomass and carbon dioxide. Ample evidence exists for aerobic biodegradation of PAHs and many bacteria capable of degrading PAHs have been isolated and characterized. However, the microbial degradation of PAHs in sediments is impaired due to the anaerobic conditions that result from the typically high oxygen demand of the organic material present in the soil, the low solubility of oxygen in water, and the slow mass transfer of oxygen from overlying water to the soil environment. For these reasons, anaerobic microbial degradation technologies could help alleviate sediment PAH contamination and offer significant advantages for cost-efficient in-situ treatment. But very little is known about the potential for anaerobic degradation of PAHs in field soils. The objectives of this research were to assess: (1) the potential for biodegradation of PAH in field aged soils under denitrification conditions, (2) to assess the potential for biodegradation of naphthalene in soil microcosms under denitrifying conditions, and (3) to assess for the existence of microorganisms in field sediments capable of degrading naphthalene via denitrification. Two kinds of soils were used in this research: Harbor Point sediment (HPS-2) and Milwaukee Harbor sediment (MHS). Results presented in this seminar indicate possible degradation of PAHs in soil under denitrifying conditions. During the two months of anaerobic degradation, total PAH removal was modest probably due to both the low availability of the PAHs and competition with other more easily degradable sources of carbon in the sediments. For both Harbor Point sediment (HPS-2) and Milwaukee Harbor sediment (MHS), PAH reduction was confined to 3- and 4-ring PAHs. Comparing PAH reductions during two months of aerobic and anaerobic biotreatment of MHS, it was found that extent of PAHreduction for anaerobic treatment was compatible with that for aerobic treatment. Interestingly, removal of PAHs from sediment particle classes (by size and density) followed similar trends for aerobic and anaerobic treatment of MHS. The majority of the PAHs removed during biotreatment came from the clay/silt fraction. In an earlier study it was shown that PAHs associated with the clay/silt fraction in MHS were more available than PAHs associated with coal-derived fraction. Therefore, although total PAH reductions were small, the removal of PAHs from the more easily available sediment fraction (clay/silt) may result in a significant environmental benefit owing to a reduction in total PAH bioavailability. By using naphthalene as a model PAH compound, biodegradation of naphthalene under denitrifying condition was assessed in microcosms containing MHS. Naphthalene spiked into MHS was degraded below detection limit within 20 days with the accompanying reduction of nitrate. With repeated addition of naphthalene and nitrate, naphthalene degradation under nitrate reducing conditions was stable over one month. Nitrite, one of the intermediates of denitrification was detected during the incubation. Also the denitrification activity of the enrichment culture from MHS slurries was verified by monitoring the production of nitrogen gas in solid fluorescence denitrification medium. Microorganisms capable of degrading naphthalene via denitrification were isolated from this enrichment culture.

• Journal of Soil and Groundwater Environment
• /
• v.6 no.3
• /
• pp.13-20
• /
• 2001

In this Study, application of ${H_2}{O_2}$/$Fe^0 oxidation System (Fenton-like oxidation) for the oxidative treatment of high-level soil contamination with hydrocarbon was suggested. The characteristics of Fenton-like oxidation of diesel-contaminated fine soil was experimentally probed in a batch system varying initial pH, zero valent iron and hydrogen peroxide levels, and initial diesel concentration. Contaminant degradation was identified by total petroleum hydrocarbon(TPH) concentration with gas chromatography. The batch experiments showed that the optimal ${H_2}{O_2}$and $Fe^0 dosage, 10% ${H_2}{O_2}$+ 20% $Fe^0 removed 65% of initial TPH concentration (10,000mg/kg) at a retention time of 24h. And the TPH removal in the ${H_2}{O_2}$/$Fe^0 system effectively proceeded only within a limited pH range of 3-4. The zero valent iron-catalyzed Fenton-like oxidation of diesel-contaminated soil was more competitive to the $FeSO_4-catalyzed system (Fenton oxidation) in removal efficiency and cost especially for the treatment of high level contamination.

• Economic and Environmental Geology
• /
• v.36 no.5
• /
• pp.349-356
• /
• 2003

As industrial activities are growing, pollutants found in the contaminated land are getting diverse. Some contaminated areas are subject to mixed wastes containing both organic and inorganic wastes such as hydrocarbon and heavy metals. This study concerns with the influence of the degradation of organic pollutants on the coexisting heavy metals, expecially for As. As mainly exists as two different oxidation state; As(III) and As(V) and the conversion between the two chemical forms may be induced by organic degradation in the soil contaminated by mixed wastes. We operated microcosm in an anaerobic chamber for 60 days, using sandy loam. The soils in the microcosm are artificially contaminated both by tetradecane and As, with different combination of As(III) and As(V); As(III):As(V) 1:1, As(III) only and As(V) only. Although not systematic, ratio of As(III)/As(Total) increase slightly at the later stage of experiment. Considering complicated geochemical reactions involving oxidation/reduction of organic materials, Mn/Fe oxides and As, the findings in the study seem to indicate the degradation of the organics is connected with the As speciation. That is to say, the As(V) can be reduced to As(III) either by direct or indirect influence induced by the organic degradation. Although Fe and Mn are good oxidising agent for the oxidation of As(III) to As(V), organic degradation may have suppressed reductive dissolution of the Fe and Mn oxides, causing the organic pollutants to retard the oxidation of As(III) to As(V) until the organic degradation ceases. The possible influence of organic degradation on the As speciation implies that the As in mixed wastes may be have elevated toxicity and mobility by partial conversion from As(V) to As(III).

• Journal of Korea Soil Environment Society
• /
• v.5 no.1
• /
• pp.97-108
• /
• 2000

A Gram-type negative bacteria that can utilize crude oil as the sole source of carbon and energy was isolated from an activated sludge of a local sewage treatment plant and identified tentatively as belonging to the genus Acinetobacter. The isolate could degrade n-alkanes and unidentified hydrocarbons in crude oil and utilize n-alkanes, hydrophobic substrates, as sole carbon and energy sources. n-Alkanes from tridecane (Cl3) to triacontane (C30) in crude oil were degraded simultaneously with no difference in degradation characteristics between the two close odd and even numbered alkanes in carbon numbers. The linear growth of the isolate and the degradation characteristics of Pr-alkanes suggested that the transport of substrates from the oil phase to the site where the substrates undergo the initial oxidation in microorganism might be the rate limiting in the biodegradation process of crude oil constituents. The remainder fraction of substrates after cultivation was considered to reflect the hydrocarbon inclusions in the cell mass, characteristics in Acinetobacter species, and to control the transport of substrates from crude oil phase. On the basis of the results, the isolate was considered to play an important role in the degradation study of hydrophobic environmental pollutants.

• Environmental Engineering Research
• /
• v.25 no.3
• /
• pp.290-298
• /
• 2020

A large residual fraction of aliphatic components of diesel prevails in soil, which has adverse effects on the environment. This study identified the most bio-recalcitrant aliphatic residual fraction of diesel through total petroleum-hydrocarbon fractional analysis. For this, the strain Acinetobacter sp. K-6 was isolated, identified, and characterized and investigated its ability to degrade diesel and n-alkanes (C₁₈, C₂₀, and C₂₂). The removal efficiency was analysed after treatment with bacteria and nutrients in various soil microcosms. The fractional analysis of diesel degradation after treatment with the bacterial strains identified C₁₈-C₂₂ hydrocarbons as the most bio-recalcitrant aliphatic fraction of diesel oil. Acinetobacter sp. K-6 degraded 59.2% of diesel oil and 56.4% of C₁₈-C₂₂ hydrocarbons in the contaminated soil. The degradation efficiency was further improved using a combinatorial approach of biostimulation and bioaugmentation, which resulted in 76.7% and 73.7% higher degradation of diesel oil and C₁₈-C₂₂ hydrocarbons, respectively. The findings of this study suggest that the removal of mid-length, non-volatile hydrocarbons is affected by the population of bio-degraders and the nutrients used in the process of remediation. A combinatorial approach, including biostimulation and bioaugmentation, could be used to effectively remove large quantities of aliphatic hydrocarbons persisting for a longer period in the soil.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.11 no.6
• /
• pp.471-476
• /
• 2006

Pseudomonas aeruginosa F722 produces a biosurfactant (BS) during its degradation of carbon and hydrocarbon compounds. The culture conditions for upgrading the biosurfactant productivity were investigated. The concentration of the biosurfactant produced by P. aeruginosa F722 was 0.78 g/L in C-medium; however, this increased to 1.66 g/L in BS medium, which was experimentally adjusted to optimal conditions. $NaNO_{2}$ was found to be most effective for microbial growth, with an $O.D_{600nm}$ of 1.18 for 0.1 % $NaNO_{2}$. Microbial growths, according to the $O.D_{600nm}$ were 2.53, 2.68, 2.89, and 2.87 for glucose, glycerol, $n-C_{10},\;and\;n-C_{22}$, respectively. Clear zone diameters (cm), indicating biosurfactant activity, were 9.0, 8.8, 5.7, and 8.5 for glucose, glycerol, $n-C_{10},\;and\;n-C_{22}$, respectively. Microbial growth was not consistent with the biosurfactant activity. The best biosurfactant activity was found with a C/N ratio of 20. Under optimal culture condition, the average surface tension decreased from 70 to 30 mN/m after 5 days. With aeration of 1.0 vvm, the biosurfactant produced increased to 1.94 g/L (up to 20%) compared to that of 1.66 g/L with no aeration. With aeration, the velocities of glucose degradation during both the log and stationary growth phases increased from 0.25 and $0.18\;h^{-1}$ to 0.33 and $0.29\;h^{-1}$, respectively, and the time for the culture to arrive at the maximum clear zone diameter became shorter, from 80 down to 60 h with no aeration.

• 보존과학연구
• /
• s.30
• /
• pp.21-29
• /
• 2009

This study shows the research of causes of deterioration of the amber from foreign cases. It also presents the conservation treatment as well as tests to examine the effect of the organic solvents on the amber in order to find reversible and safe reinforcing agent which will prevent further damage of the artefact. The result showed that there was no noticeable change in the weight of the artefact as well as on the appearance of the surface when Mineral spirit(White spirit), which is aliphatic hydrocarbon group, and Xylene, aromatic hydrocarbons group was applied. Reinforcement and restoration was carried out using Paraloid(R) B67, which has a broad option for the solvent, in Xylene. Finally, it is recommended that the use of polar organic solvent in the conservation treatment of amber artefacts should be limited.